Example EUVS-C Observations. Left: spectra with 0.1 nm resolution plotted in corrected data numbers collected during a 3-second integration (DPRIME, see Sect. 5.2) for two dates 14 days apart (half a solar rotation). These dates were chosen because there was a single large active region on the solar disk that rotated into view on October 10, 2022. Right: ratio of the spectra shown on the left panel. Strong variability is evident in the h and k emission lines relative to adjacent wavelengths.